the same doctor who did brennan ber berry's implant surgery. >> his name is dr. rosen. dr. randy rosen. >> reporter: that recruiter from craigslist had also told bus him. >> excuse me, dr. roseen? >> reporter: rosen declined our request for an interview. so we tried to catch up with him outside his office. >> but we've been wanting to talk to you about why patients are being paid to get surgery. >> reporter: through his attorney dr. rosen said he has nothing to do with that craigslist ad and he has no idea who carter is. >> this is private property. you guys are not allowed to come in here. >> reporter: he also told us all patients must sign this form stating they have not been paid to get the implants. as for brennan berry, three months after getting his he overdosed after taking heroin mixed with fentanyl. >> i came home and found him. i'm in his bedroom, and he was gone when i got here. >> you saw him struggle with this. >> you wake up every day and you have to fight every day not to use or not to drink. they say it's one day at a time, but it's every second of every day

. >> reporter: in march 2016, debbie berry got a text from her 22-year-old son brennan that no mothereceive. >> he texted me and said i have a drug problem, mama, i'm in trouble. >> reporter: desperate to help her son, berry got him into treatment in california. one day he called her from a doctor's office to tell her he'd found something to help. >> he said, i'm going to get an implant put in. i'm here with them and they've done a precertification that the insurance -- your insurance will pay for it. >> reporter: it was an naltrexone transplant. a small pellet inserted near the abdomen. it releases medication that blocks the brain's opoid receptors. if he used heroin, he would not be able to feel the effects. >> he was so adamant about how much it would help him. >> reporter: did you know he was getting paid for it? >> i absolutely did not know he was getting paid for it. >> reporter: a cbs news investigation has found vulnerable addicts like brennan berry are being paid hundreds, sometimes thousands of dollars in cash, to get this 30-minute outpatient procedure. >> you doesn't give